What causes "failed to create CPU profile: %w" in gohugoio/hugo?

Verify the parent directory exists and is writable, then re-run `hugo --cpuprofile= `.

failed to create CPU profile

Error message

failed to create CPU profile: %w

What it means

Hugo's `hugoBuilder.initCPUProfile` calls `os.Create(c.r.cpuprofile)` to open the output file for a Go CPU profile (set via `--cpuprofile`). This error wraps the OS-level file creation failure. It fires before any profiling starts, so the process has not yet begun capturing samples.

Solutions

Verify the parent directory exists and is writable, then re-run `hugo --cpuprofile=<abs/path/cpu.prof>`.
Use an absolute path under a directory you own (e.g. `~/cpu.prof`) instead of a bare filename.
Drop `--cpuprofile` entirely if you do not need profiling — `initCPUProfile` is a no-op when the flag is empty.

Example fix

// before
// $ hugo --cpuprofile=/var/run/cpu.prof
// after
// $ mkdir -p /tmp/hugoprof && hugo --cpuprofile=/tmp/hugoprof/cpu.prof

Defensive patterns

Strategy: validation

Validate before calling

// Validate writability before launching Hugo with --cpuprofile.
import (
  "os"
  "path/filepath"
)
func validateProfilePath(p string) error {
  dir := filepath.Dir(p)
  info, err := os.Stat(dir)
  if err != nil { return err }
  if !info.IsDir() { return os.ErrNotExist }
  // probe writability
  f, err := os.CreateTemp(dir, ".hugocpu-*")
  if err != nil { return err }
  f.Close(); os.Remove(f.Name())
  return nil
}

Type guard

null

Try / catch

null

Prevention

Always pass an absolute `--cpuprofile` path under a writable directory you own.
Pre-flight check that the parent directory exists before running `hugo --cpuprofile`.
Leave the flag unset during normal builds to skip profiling entirely.

When it happens

Trigger: Invoked when `c.r.cpuprofile != ""` (the `--cpuprofile` flag was passed) and `os.Create` returns a non-nil error — e.g. a directory in the path does not exist, the path is read-only, or the user lacks write permission.

Common situations: Passing a relative `--cpuprofile=cpu.prof` from a working directory that is not writable; pointing the flag at an unwritable or non-existent directory like `/var/log/cpu.prof`; a typo in the path including a missing parent directory.

Related errors

AI-assisted analysis of gohugoio/hugo@52c9bd7908 (2026-08-09). Data as JSON: /api/errors/2989d35e3f3f3773. Report an issue: GitHub.

Appendix: source

Thrown at commands/hugobuilder.go:179

// getDirList provides NewWatcher() with a list of directories to watch for changes.
func (c *hugoBuilder) getDirList() ([]string, error) {
	h, err := c.hugo()
	if err != nil {
		return nil, err
	}

	return hstrings.UniqueStringsSorted(h.PathSpec.BaseFs.WatchFilenames()), nil
}

func (c *hugoBuilder) initCPUProfile() (func(), error) {
	if c.r.cpuprofile == "" {
		return nil, nil
	}

	f, err := os.Create(c.r.cpuprofile)
	if err != nil {
		return nil, fmt.Errorf("failed to create CPU profile: %w", err)
	}
	if err := pprof.StartCPUProfile(f); err != nil {
		f.Close()
		return nil, fmt.Errorf("failed to start CPU profile: %w", err)
	}
	return func() {
		pprof.StopCPUProfile()
		f.Close()
	}, nil
}

func (c *hugoBuilder) initMemProfile() {
	if c.r.memprofile == "" {
		return
	}

	f, err := os.Create(c.r.memprofile)
	if err != nil {

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